水杨酸甲酯清除羟基自由基活性的研究

利用脉冲辐解技术研究了水杨酸甲酯清除羟基自由基反应的瞬态吸收谱,测定了水杨酸甲酯与羟基自由基反应的表观速率常数。辅以常规检测方法,测定了水杨酸甲酯对羟基自由基的清除率。结果表明,水杨酸甲酯能快速有效清除羟基自由基。探讨了水杨酸甲酯清除羟基自由基的反应机制。     

Phase equilibria for binary systems of octane boosters with 2,2,4-trimethylpentane

Isobaric vapor–liquid equilibrium data at 95.96 kPa for the three binary systems of 2,2,4-trimethylpentane with methyl tert-butyl ether, di-isopropyl ether and dimethoxymethane are determined. A Swietoslawski type ebulliometer is used for the measurements. The experimental T–x data are used to estimate Wilson parameters and the parameters, in turn, are used to calculate vapor phase compositions and activity coefficients. All the systems studied here do not exhibit azeotropes and behave like non-ideal solutions.     

疏水相互作用对阳离子聚电解质与染料键合的影响

用平衡渗析法研究了阳离子聚电解质PAm·MG 和P(St-Am·MG)与甲基橙(MO)及P(St-Am·MG)与MO的同系物乙基橙(EO)、橙武Ⅳ(O-Ⅳ)在25、35、45和55 ℃下相互作用的热力学. 由K1otz方程, 求得键合常数K_1和热力学参数ΔG、ΔH及ΔS. 含疏水基的P(St-Am·MG)与MO的键合能力比不含疏水基的PAm·MG 强. P(St-Am·MG)与不同染料作用时, 键合程度为O-Ⅳ>EO>MO, 即染料的疏水性越强, 与高聚物的作用程度越大.键合体系加入脲或甲醇, 疏水相互作用受到破坏, 导致高聚物与染料之间的键合受到削弱.     

硝酸甲酯分子间相互作用的DFT和ab initio比较

用密度泛函理论(DFT)和从头算(ab initio)方法,分别在B3LYP/6 31G和HF/6 31G水平上求得硝酸甲酯三种二聚体的全优化几何构型和电子结构,并用6 311G和6 311＋＋G基组进行总能量计算.对HF/6 31G计算结果进行MP4SDTQ电子相关校正.在各基组下均进行基组叠加误差(BSSE)和零点能(ZPE)校正求得结合能.对6 31G优化构型作振动分析并基于统计热力学求得200～600 K温度下单体和二聚体的热力学性质.详细比较两种方法的相应计算结果,发现DFT求得的分子间距离较短,分子内键长较长,所得结合能均小于相应ab initio计算值.     

可交联聚甲基丙烯酸甲酯的合成、表征及在阵列式波导光栅中的应用

合成了含环氧基团的可交联的甲基丙烯酸甲酯和甲基丙烯酸环氧丙酯的共聚物[Poly(MMA-co-GMA)],通过FTIR,NMR,GPC,DSC和AFM等技术对其进行了表征. 结果表明,所合成的聚合物材料具有较好的成膜性; 通过热固化使引入的环氧基团开环交联,该聚合物的玻璃化转变温度(Tg)比固化前提高了24 K,同时有效地降低了聚合物的双折射率. 用Poly(MMA-co-GMA)作为包层材料,双酚A型环氧化合物作为高折射率材料, 将其引入到包层材料中形成芯层材料的折射率在波长1.55 μm处可调,其范围是1.483~1.588. 采用旋涂、 铝掩膜和氧反应离子刻蚀的方法(RIE)制得了阵列式光波导. 测试结果表明,制作的波导在1.55 μm处实现了光的单模传输,光损小于3.0 dB/cm.      

Study on the Tautomer Interconversion of 3-Oxo Pentanoate During Gas Chromatography

Enol and keto tautomers of methyl 3-oxo pentanoate could be separated on a HP-5 capillary column. The chromatographic peaks were identified by examining characteristic mass ions arose from the corresponding enol and keto molecular ions. The study showed that the area percentage of enol tautomer is a function of temperature of the column. Treating the column as a reactor, the energy of activation for the on-column tautomerization could be extracted (35.1 kJ mol⁻¹) by monitoring the loss of the enol tautomer, because the reaction is found to obey pseudo first-order kinetics. The enthalpy and the entropy changes (ΔH = −3.98 kJ mol⁻¹, ΔS = −7.89 J K⁻¹mol⁻¹) for the enol-to-keto reaction in the stationary phase were also obtained.     

Degradation-fragmentation of marine plastic waste and their environmental implications: A critical review

This review critically evaluates the plastic accumulation challenges and their environmental (primarily) and human (secondarily) impacts. It also emphasizes on their degradation and fragmentation phenomena under marine conditions. In addition, it takes into account the leachability of the various chemical substances (additives) embedded in plastic products to improve their polymeric properties and extend their life. Regardless of their effectiveness in enhancing the polymeric function of plastic products, these additives can potentially contaminate air, soil, food, and water. Several findings have shown that, regardless of their types and sizes, plastics can be degraded and/or fragmented under marine conditions. Therefore, the estimation of fragmentation and degradation rates via a reliable developed model is required to better understand the marine environmental status. The main parameter, which is responsible for initiating the fragmentation of plastics, is sunlight/UV radiation. Yet, UV- radiation alone is not enough to fragment some plastic polymer types under marine conditions, additional factors are needed such as mechanical abrasion. It should be also mentioned that most current studies on plastic degradation and fragmentation centered on the primary stages of degradation. Thus, further studies are needed to better understand these phenomena and to identify their fate and environmental effects.     

BARRIER PROPERTIES OF VINYLIDENE CHLORIDE/METHYL ACRYLATE COPOLYMER

A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) ascomonomer (3--12wt%), was prepared by free-radical suspension copolymerization. Thepermeability coefficients of the copolymers to oxygen and carbon dioxide were measured at1.0 MPa and at 30℃, and those to water vapor were measured at 30℃ and 100% relativehumidity All the VDC/MA copolymers studied are semicrystalline. As the MA contentincreases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, andwater vapor are progressively increased, caused by decrease in crystalline fraction andincrease in free volume of VDC/MA copolymers.     

甲基化的β-环糊精与十六烷基三甲基溴化胺的相互作用

环糊精与表面活性剂的相互作用已有许多研究,但多局限于β－环糊精（β－CD）,而修饰的β－环糊精与表面活性剂的相互作用研究较少[1－3]．分子内扭转电荷转移（TICT）激发态对介质极性高度敏感性,已成功地用于探针环糊精与表面活性剂的相互作用[4]．研究表明,β－CD能够诱     

Voltammetric Determination of Trace Amounts of 2‐Methyl‐4,6‐Dinitrophenol at a Silver Solid Amalgam Electrode

The voltammetric behavior of 2‐methyl‐4,6‐dinitrophenol was investigated by differential pulse voltammetry (DPV) at a nontoxic mercury meniscus‐modified silver solid amalgam electrode (m‐AgSAE). Conditions have been found for its determination by DPV at m‐AgSAE in the concentration range of 0.2 to 1 μmol L^?1.